# LinkedList - 61. Rotate List

61. Rotate List

Given a linked list, rotate the list to the right by k places, where k is non-negative.

Example 1:

Input: 1->2->3->4->5->NULL, k = 2
Output: 4->5->1->2->3->NULL
Explanation:
rotate 1 steps to the right: 5->1->2->3->4->NULL
rotate 2 steps to the right: 4->5->1->2->3->NULL

Example 2:

Input: 0->1->2->NULL, k = 4
Output: 2->0->1->NULL
Explanation:
rotate 1 steps to the right: 2->0->1->NULL
rotate 2 steps to the right: 1->2->0->NULL
rotate 3 steps to the right: 0->1->2->NULL
rotate 4 steps to the right: 2->0->1->NULL

java ：

``````/**

* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode rotateRight(ListNode head, int k) {

ListNode dummy = new ListNode(0);

ListNode fast = dummy, slow = dummy;
int len; // get list len;
for (len = 0; fast.next != null; len++) fast = fast.next;

// find rotate node
for (int i = len - k % len; i > 0; i--) slow = slow.next;

// rotate
fast.next = dummy.next;
dummy.next = slow.next;
slow.next = null;

return dummy.next;
}
}
``````

Nothing just happens, it's all part of a plan.